Signal Processing Circuit for Avalanche Photodiode Noise Removal
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Solution Overview
Problem
Existing signal processing circuits for light detecting devices with avalanche photodiodes struggle to enhance the transmission rate of signals to succeeding-stage circuits while maintaining precision in noise removal.
Innovation Solution
The integration of an AC coupling unit and a level shifter unit reduces parasitic capacitance and increases the speed of signal transmission. Additionally, a reference value adjustment unit is included to adjust the reference value of the signal input to the comparison circuit, ensuring precise noise removal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If an AC coupling unit is provided between the avalanche photodiode and the succeeding-stage circuit, then the signal transmission rate is improved, but the parasitic capacitance between the avalanche photodiode and the comparison circuit increases
Solution Approach 1:
The AC coupling unit acts as an intermediary component between the avalanche photodiode and the comparison circuit. By introducing this coupling capacitor, the circuit achieves AC signal transmission while blocking DC components, thereby improving signal transmission rate while managing parasitic capacitance effects through proper capacitor selection and circuit design.
Solution Approach 2:
The invention adjusts circuit parameters including the capacitance value of the AC coupling unit and the bias voltage applied to the avalanche photodiode. By optimizing these parameters, the circuit achieves high signal transmission rate while controlling the impact of parasitic capacitance on overall circuit performance.
2Measurement precision
If a comparison circuit is provided to remove noise components, then the measurement precision is improved, but the transmission rate of the signal to the succeeding-stage circuit decreases
Solution Approach 1:
The comparison circuit performs noise removal in advance before the signal reaches the succeeding-stage circuit. By pre-processing the signal to eliminate noise components through threshold comparison, the circuit achieves high measurement precision while maintaining transmission rate through efficient comparator design with minimal propagation delay.
Solution Approach 2:
The invention replaces complex analog filtering mechanisms with a digital comparison-based noise removal approach. The comparison circuit uses threshold voltage comparison instead of traditional RC filtering, achieving superior noise rejection with faster response time and minimal impact on signal transmission rate.
3Measurement precision
If the voltage applied to the avalanche photodiode is increased to improve photon detection efficiency, then the detection accuracy is improved, but the power consumption increases
Solution Approach 1:
The invention optimizes the bias voltage parameter applied to the avalanche photodiode to achieve the optimal balance between photon detection efficiency and power consumption. By carefully selecting and adjusting the reverse bias voltage, the circuit achieves high detection accuracy while minimizing excessive power consumption through precise parameter control.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration significantly improves the transmission rate of signals to succeeding-stage circuits while ensuring the precision of noise removal, enhancing the detection accuracy of light incident on the avalanche photodiode.
Implementation Method 1
This configuration reduces the parasitic capacitance between the avalanche photodiode and the comparison circuit in the AC coupling unit, increasing the speed of the variation in the signal output from the avalanche photodiode.
Implementation Method 2
an avalanche photodiode operating in Geiger mode
Implementation Method 3
an avalanche photodiode operating in Geiger mode is connected to a signal processing circuit
Data Source
AI summary
In a signal processing circuit, an input terminal is configured to receive an analog signal output from an avalanche photodiode operating in Geiger mode. A comparison circuit outputs a signal based on a component exceeding a threshold among components a signal input to the comparison circuit. The adjustment circuit includes an AC coupling unit, a level shifter unit, and a reference value adjustment unit. The AC coupling unit establishes AC coupling between the input terminal and the comparison circuit. The level shifter unit adjusts the voltage of the signal input to the comparison circuit to a value lower than a reverse bias voltage applied to the avalanche photodiode. The reference value adjustment unit adjusts the reference value of the signal input to the comparison circuit.